Aircraft comprise many on-board items of electrical, mechanical and data-processing equipment. The functioning of these on-board items of equipment, whose processing is necessary for the correct progress of the flight, is monitored notably by the crew of the aircraft during the flight. Any failure of one of the items of equipment can be reported either by the crew of the aircraft, or by the equipment itself, or by an on-board maintenance equipment to which the equipment can be connected. Once back on the ground, all of the data relating to possible failures are collected and then analysed by a ground maintenance team. One of the challenges of aircraft maintenance is to be able to identify critical failures of on-board items of equipment, as well as their sources, as quickly as possible in order to apply a quick correction and in order to prevent as far as possible an immobilization of an aircraft on the ground, which is very costly for airline companies.
In aircraft, a centralized maintenance system can collect failure indicators coming from the items of equipment of the aircraft as well as warnings intended for the crew of the aircraft. The centralized maintenance system also has some operational context data such as general parameters relating to the aircraft, for example: a date, a timestamp, a flight phase, a maintenance phase, an aircraft type, a registration of the aircraft, a flight number, a departure airport, an arrival airport. The centralized maintenance system carries out a temporal correlation between the failures and the warnings transmitted to the crew as well as a correlation between the failures of the different items of equipment of the aircraft.
For example, one failure is often spotted by aircraft pilots: a failure of the aircraft's radio altimeter. A radio altimeter is a system giving the altitude of the aircraft with respect to the ground. A range of validity of a radio altimeter measurement is typically between zero and two thousand five hundred feet. The radio altimeter does not give an indication of altitude above two thousand five hundred feet. Some pilots enter the following incident in a logbook of the aircraft: “radio altimeter failure, UTC”. UTC is an acronym for “Coordinated Universal Time”. Once the aircraft is on the ground, a maintenance officer is responsible for putting the aircraft back into a good operational state with respect to the incidents recorded in the logbook. In the case of the incident taken as an example regarding the radio altimeter, no crew warning was raised by an on-board FWS connected to the items of equipment. An FWS is a “Flight Warning System”. Moreover, no failure of an LRU was detected by the centralized maintenance system. LRU is an acronym for “Line Replaceable Unit”, which denotes an equipment installed on-board an aircraft. The maintenance operator therefore has no additional information for carrying out a diagnosis of the incident mentioned in the logbook. In such a case, the maintenance operator consults a maintenance manual of the aircraft in order to initiate a test on the radio altimeter. The test makes it possible to conclude that the radio altimeter is in a correct operating state, which is the case. It is therefore a matter of a false failure, noted by the pilot without there having been a failure.
Such false failures cause the maintenance crew to waste valuable time on the ground. They can possibly mask serious failures, which are critical for the aircraft.